Temperature compensated gauge



y 15, 1952 R. 5. FOX EI'AL TEMPERATURE COMPENSATED GAUGE Filed March 1, 1945 l l l l O INVENTORS mond 6. F0); DXf/jl:

AYMME)" AZb' IfIM Patented July 15, 1952 i UNITED STA ES I T MPERATURE coMPENsA'rED .VGAUGE' Raymond's. Fox, West Hartford, and Albert Dexter, Jr.,, Farmington, Conn., assignors to Niles-Bement-Pond Company, West Hartford,

Conn., a corporation of New Jersey 1 7 Application Marchjl, 1945, Serial No. 5s0,4 30

The present invention relates to dimension gages and particularly to a 'gage for continuously measuring the thickness of a strip of metal or other material while it is being rolled or otherwise processed and while being rapidly traversed between the work engaging members of the'gage.

With the rolling mill speeds used in the past, gages of the type described herein have been sufficiently accurate without any provision bein required for correcting errorsintroduced by temperature variations in the'members of the gage. However, with increased demands for high pref cision and increased production of steel, there has been a considerable demand for greatly increased rolling speeds. Since the strip being rolled becomes heated, the temperature of .parts of the gage nearer the'strip tends to increase during operation. 'Also the rapidrotation of the work engaging members within their "bearings causes them to increase in temperature. 7 I

The present'invention is illustrated and described as' applied to a continuous gage of the type shown in the patents to Spencer? B. Terry et al. No. 2,115,351, granted April 26, 193 8'and to Spencer B.,.Terry No- 2,137,368, granted November 22, 1938. 'It will be understood, howevenlthat'the temperature compensating nieansmay be applied to any dimension gage of the electricaltype havingabridgecircuit. Q r 4 ,4 7 An object of the invention is to "provide, in' a gage of the type described, meansfor coinpen} sating the gage for variations in the temperature of the difierent parts of the gage structure. Another object is to provide, in a, age'of the type described, means responsive to the temperature of one of the work contacting elements of the gage for compensating any error due to changes in such temperature. I

Another object is to provide, in the electrical circuit of a dimension gage, an element having'an electrical characteristic variable with temperature for compensating the, gage for errors due to temperature changes. v I

A feature of importance of the invention is that the compensation element may be aresistance element having a negative'temperature-coefficient, this element being insertedinfone side of the bridge forming a part of 'the electrical circuit of the gage. 1

With the above and other objects in view, the invention comprises the features oflconstruction and operation set forth in the followingspecifi cation and illustrated in the accompanying draw Inga h Inthe accompanying drawings annexed hereto 3Clainis. (o1.33 147) and forming a part of'this specification, we have shown the invention embodied in a particular form of gage for gaging all types of metals while being rolled, into relatively thin'sheets or strips, but it will be understood that'the invention'can be otherwise embodied and that the drawings are not to be construed as defining Orlimiting the scope of the invention, the claims appended to this specification being relied upon for that purpose.- o I In thedrawings:

Figure 1 is a side elevational view'of a complete gaging head with a portion ofits structure cut away to illustrate the structure, of the temperature compensating element used in .thegagdj, Fig. 2 is an enlarged cross sectionalview of one of the 'work engaging members and the arbor on which it is mounted,fshowing the temperature compensating element mountedwithin thearbor and t V Fig. 3 is an electric wiring diagram showing a preferred form of circuit used with 'thejg e shown in Figs; 1 and 2 and'in which is included the temperature compensating'element.

In the, above mentioned drawings "there has been shown but one embodiment of the'invention which isnow deemed preferable, but it is to be understood that changes andmo'difications may be made withinthe scope of the appended claims without departing from the spirit of the invention. f' J Briefly, and in its'preferred aspect, 'the'inven tion may include the following principal partsf First, a'pair of work engaging membersj'adapted to contact opposite surfacesjjof the work being gaged, the members shown comprising rolls" the indicating instrument for errors introj'du ed by variations in .be'rs. "Referring more in detail to the individual fig: ures of the drawing, there .is illustrated 'a' frame temperature. of the gage meni or body member H! which supports a pair of rolls l2 and [4 for engagement with the opposite sides of a work piece or strip W.

The upper roll [4 is supported on a slide I6 which is vertically movable within the frame member l and is biased into engagement with the work piece by a spring [8. The normal vertical position of the slide l6 and roll l4 may be adjusted by means of a micrometer screw having a hand wheel associated therewith for varying the adjustment and an indicating counter 22 for indicating the work thickness the adjustment for which the roll is set. A button 24 associated with the slide l6 engages a button 26 on one end of an armature 28. The armature 28 is fulcrumed at its center and its opposite end lies between a pair of coils 38 and 32, which are connected in an electrical bridge circuit illustrated in Fig. 3.

The slide l6 and its related supporting, adjusting and adjustment indicating elements are shown and described in detail in the patents to Terry et a1. and Terry referred to above. It is believed that further description of these mechanical elements will therefore be unnecessary.

The lower roll I2 is journaled on a fixed arbor 34 mounted in the frame l0. Anti-friction bearings 36 between the roll I2 and the arbor 34 permit ready rotation of the roll when the work being gaged is passed through the gage. The end of arbor 3 4 which projects inside the hollow casformed by frame [0. is provided with an axially extending bore 38. An electrical connector 46is'threaded on the end of the arbor 34. A pair of electrical conductors 42 and 44 pass through the connecter 40. and into the bore 38 in the arb'or 34. Inside the, bore 38, these two cbnductorsfare attached to and support an electrical resistance element 68. The element 68 is preferably of carbon or other suitable electrical resistance material having appreciable negative temr'aerature ooeflicient of resistance. This element 68 at higher temperature becomes less resistant to current flow instead of becoming more resistant as in the case, of most metal conductors such as copper. It is by means of this negative resistance characteristic of element 68 that temperature, compensations, are effected.

Fig. 3 illustrates an electrical bridge circuitin which the impedance coils and 32 and the resistance, element 68. areconnected. The bridge circuit in Fig. 3 has, a pair of input terminals 48v and 58. and a pair of, output terminals 52. and 54 The input terminals 48 and 50 may be and preferably are connected to, the opposite. ends offthe. secondary of a transformer 5|; thepridiary of which receives its voltage from anysuiteblefsource. In each of the two arms of the bridgecircuit which connect the input terminal 58. to the respective output, terminals 52 and 54 isjone of a pair of fixed impedances, 56 and 58. The. impedance 5,6. is connected between: input terminal 56 and output terminal 52 and the. fixed impedance 58 is connected between input terinitial 50 and output terminal 54. The two. coils 38 and 32 are connected at their central points tolthe input terminal, 48 and at their opposite ends. to, the respective output terminals, 52 and 54 of the bridge circuit. The connection be-v tween input terminal 48. and'output terminal 52 maybe traced from terminal 48 throug-h a, con.- ductor 60, and coil 36 to output terminal 52. The connection between input terminal 48 and outputterminal 54 may likewise be, traced through conductor 60 and coil 32.

Connected in parallel with the arm of the bridge which includes the coil 38, is a branch including the fixed resistance 46 and a manually adjustable resistance 62. This parallel branch may be traced from input terminal 48 through a conductor 64, fixed resistance element46, the adjustable resistance 62, and the conductor 66 to output terminal 52.

Connected in parallel with the arm of the bridge which includes coil 32 is another branch which may be traced from input terminal 48 through a negative coeificient resistance 68, a manually adjustable resistance 10, and a conductor 12 to output terminal 54.

The adjustable resistance 62, together with the fixed resistance 46, determines the total resistance between input terminal 48 and output terminal 52 which must be balanced by the total resistance between input terminal 48 and output terminal 54 if the output of the branches of the bridge circuit is to be equal and opposite and thus'zero. The adjustable resistance 62 is therefore termed the zero adjustment of the bridge circuit and the resistance 46 the balancing resistance.

The adjustable resistance 10 determines the efiect which a given change in the variable resistance of element 68 will have upon the unbalance of the bridge circuit. For example, if all the resistance or element 10 is connected in series with elements 68, then the percentage change in the total resistance between input terminal 48 and output terminal 54 caused by a given change in resistance of element 68 due to a temperature change, is relatively small. On the other hand, if resistance 10 is adjusted so that its value is substantially zero, then the same change in resistance of element 68 will produce a relatively large percentage change in the total resistance between input terminal 48 and output terminal54. The manually adjustable resistance i0 is therefore termed the sensitivity adjustmen Electrical power is supplied to the bridge circuit through a transformer 14, the primary or which may be connected to an available A. C. power supply, although it will be readily understood that any other suitable source may be used. The output oi the bridge circuit is rectified by a plate or bridge rectifier illustrated at 16 and the rectified output is supplied to a milliammeter 18 or other electrical indicating instrument preferably having a central zerov on its scale. If desired, any other suitable measuring or controlling instrument might be used in place or milliammeter 18.

With the exception of the temperature compensating member 68, the circuit shown in Fig. 3 is similar to those made use of intheTerry'et a1. and Terry patents referred; to above. Similar bridge circuits in dimension gages are also shown and described in the patents to Mershon 1,640,464 and Hathaway 2,240,184, and in numerous other patents. As no claim ismade to the circuit described in this application, except when anciement having a negative resistance characteristie is employed in one side oi the bridge, no further description of the circuit is thought to be necessary.

hen. a sage o hi t e sin, use he rolls tend. w eat o than heframe e a e t e rolls are, in direct contact with the strip which is heated by the rolling process and in addition because they are heated, byrotation on their bearings. On the other hand the mass of the frame makes it slower to change its temperature. As the rolls become heated and expand slightly, the upper roll 30 tends to be forced upwardly so that it indicates that the strip is thicker than it actually is. The slower and less temperature rise of the gage frame has much less effect on the indicated dimension. Its effect is to indicate on the indicator a less dimension of the work than it actually is. The difierence between these errors is substantially corrected by the introduction of the negative coeflicient resistance element 68. Therefore, in order to provide temperature compensation the temperature sensitive element 68 must be placed in the aircuit and operate in such a manner as to decrease the reading of themeter '13 as the temperature increases.

As the measuring rolls l2 and I4 expand due to their higher temperatures the slide I6 is moved upwardly, thereby moving the button 24 upwardly and causing the armature 28 to rotate in an anti-clockwise direction, as viewed in Fig. 1, about its central fulcrum. Therefore the left end of armature 28 as seen in Fig. 1 is moved downwardly toward coil 32 and away from coil 30. The impedance of coil 32 is thereby increased and the impedance of coil 30 is decreased. The meter 18 is so connected to the bridge circuit that an unbalance of the impedances of the two coils 30 and 32 in this sense produces a high reading on the meter. However, if this high reading is due to the temperature of the rolls, then the resistance element 68 comes into play. Since it is chosen from a class of resistances having a negative coefiicient, its resistance decreases when the temperature rises and the impedance of that side of the bridge which includes coil 32 increases. Therefore it compensates for the increased impedance of coil 32, with which it is connected in parallel. If the sensitivity and zero adjustments are properly made by resistances B2 and 10, respectively, the decrease in the resistance of element 68 may be made to compensate substantially for errors in the reading of the meter due to erroneous unbalance of the coils 30 and 32 because of temperature conditions.

The introduction of the negative coefiicient resistance element 68 into one side of the bridge circuit does not affect the voltage between the output terminals '52 and 54 when the bridge is unbalanced by movement of the armature 28 and the temperature remains normal. The resistance element 68 therefore does not vary the magnification of the gage to any appreciable degree. Corresponding displacements of the armature 28 will give corresponding displacements of the pointer of the indicating instrument 18 with or without the resistance element 68 included in the circuit. No changes, therefore, will be required in the characteristics of the indicating instrument used with the present circuit over those of the instrument used in the circuit of the above-mentioned patent.

What we claim is:

1. Temperature compensating means for a dimension gage comprising a pair of work contacting members for engaging opposite sides of a work piece, frame means for relatively adjustably supporting said work contacting members, an electric indicating instrument for indicating variations from the adjusted spacing of said contacting members, a bridge circuit for said indicating instrument, and an element having a negative resistance characteristic in one of the branches of said circuit for compensating the readings of said indicating instrument during gaging operations for errors introduced by temperature variations.

2. Temperature compensating means for a dimension gage comprising a pair of work contacting members for engaging opposite sides of a work piece, frame means for relatively adjustably supporting said work contacting members, an electric indicating instrument for indicating variations from the adjusted spacing of said contacting members, a bridge circuit for said indicating instrument, and an element having a, negative resistance characteristic in one branch of said bridge circuit for compensating the readings of said indicating instrument during gaging operations for errors introduced by temperature variations.

3. Temperature compensating means for a dimension gage comprising a pair of contacting members for engaging opposite sides of a work piece, frame means for relatively adjustably supporting said contacting members, means associated with said frame means for indicating the spacing of said contacting members and thereby indicating the thickness of the work piece at normal temperature, an electrical indicating instrument having a bridge circuit for indicating variations from the adjusted spacing of said contacting members, and an element having a negative resistance characteristic for varying the impedance in one side of said bridge circuit for said electrical indicating instrument during gaging operations to eliminate errors introduced by temperature variations, said element being housed within one of the work contacting members.

RAYMOND S. FOX. ALBERT M. DEXTER, JR.

REFERENCES CITED The' following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,115,351 Terry Apr. 26, 1938 2,137,368 Terry Nov. 22, 1938 2,165,647 Oehmichen July 11, 1939 2,276,816 Bagno Mar. 17, 1942 2,323,267 Wittkuhns et al. June 29, 1943 2,344,642 Ruge Mar. 21, 1944 2,370,609 Wilson Feb. 27, 1945 2,396,420 Hayward et al. Mar. 12, 1946 

